The invention relates broadly to the charge pumps that are commonly employed in electrically erasable programmable read only memory (EEPROM) integrated circuit (IC) chips. The basic circuit operates at a relatively low voltage, such as 3 V or 5 V, but some of the circuit functions require a substantially higher voltage such as an internal 15 volts. This higher voltage is typically provided by means of an on chip charge pump form of voltage multiplier. The charge pump is made up of a plurality of stages driven from a plural phase clock. Typically, the clock is operated at a predetermined frequency and is operated continuously so that the highest available value of boosted voltage is present. Then, a voltage regulator is employed to drop the voltage to the desired level. Since the current required from the boosted voltage is typically low, a shunt regulator can be employed.
This form of on chip high voltage generation is wasteful of power because the excess voltage is reduced by a regulated current drain. The circuits are slow to start because a large number of clock cycles must be employed to produce the high voltage.